title: Improvement of intensive care unit sound environment and analyses of consequences on sleep: an experimental study.
abstract: OBJECTIVE
  Uninterrupted sleep is of vital importance for restoration and regaining health. In intensive care units (ICUs) where recovering and healing is crucial, patients' sleep often is fragmented and disturbed due to noise from activities from oneself, other patients, and alarms. The aim of our study was to explore if sleep could be improved by modifying the sound environment in a way that is practically feasible in ICUs.
  
  
  METHODS
  We studied the effects of originally recorded ICU noise and peak reduced ICU noise on sleep in healthy male participants. Sleep was registered with polysomnography (PSG) during four nights: one adaptation night, one reference (REF) night, and the two exposed nights with similar equivalent sound levels (47dB LAeq) but different maximum sound levels (56- vs 64-dB LAFmax). The participants answered questionnaires and saliva cortisol was sampled in the morning.
  
  
  RESULTS
  During ICU exposure nights, sleep was more fragmented with less slow-wave sleep (SWS), more arousals, and more time awake. The effects of reduced maximum sound level were minor. The subjective data supported the polysomnographic findings, though cortisol levels were not significantly affected by the exposure conditions.
  
  
  CONCLUSIONS
  Noise in ICUs impairs sleep and the reduction of maximal A-weighted levels from 64 to 56dB is not enough to have a clear improved effect on sleep quality.
authors.affiliation: Department of Occupational and Environmental Medicine, Gothenburg University, Medicinaregatan 16, 405 30 Göteborg, Sweden. Electronic address: Kerstin.persson.waye@amm.gu.se.
authors.forename: Kerstin
authors.initials: K
authors.lastname: Persson Waye
authors.forename: Eva-Maria
authors.initials: EM
authors.lastname: Elmenhorst
authors.forename: Ilona
authors.initials: I
authors.lastname: Croy
authors.forename: Eja
authors.initials: E
authors.lastname: Pedersen
mesh_terms: D000293:Adolescent; D000328:Adult; D004779:Environment Design; D064368:Healthy Volunteers; D006801:Humans; D006854:Hydrocortisone / Q000378:metabolism; D007362:Intensive Care Units; D008297:Male; D009622:Noise / Q000009:adverse effects* / Q000517:prevention & control*; D017286:Polysomnography; D012892:Sleep Deprivation / Q000209:etiology*; D012894:Sleep Stages; D012895:Sleep, REM; D011795:Surveys and Questionnaires; D014851:Wakefulness; D055815:Young Adult
chemical_list: D006854:Hydrocortisone
keywords: Arousal; Cortisol; Experimental; Intensive care; Noise; Sleep; Sound